From: Type I error rates of multi-arm multi-stage clinical trials: strong control and impact of intermediate outcomes
Stage (j)
Target
Outcome
One-sided significance
Power (ω j )
Required control
HR
level (α j )
arm events
1
0.75
FFS
0.500
0.95
113
2
0.250
216
3
0.100
334
4
OS
0.025
0.90
403
Overall
0.013
0.83